A Comparative Study Between Gaofen-1 WFV and Sentinel MSI Imagery for Fire Severity Assessment in a Karst Region, China

Wild fires frequently influence fragile karst forest ecosystems in southwestern China. We evaluated the potential of Gaofen Wide Field of View (WFV) imagery for assessing the fire severity of karst forest fires. Comparison with Sentinel Multispectral Imager (MSI) imagery was conducted using 19 spectral indices. The highest correlation for Sentinel-2 MSI is 0.634, while for Gaofen-1 WFV it is 0.583. This is not a significant difference. The burned area index, differenced burned area index, and relative differenced modified soil adjusted vegetation index were the highest performing indices for the Gaofen-1 WFV, while the normalized burn ratio plus, differenced normalized differential vegetation index, and relative differenced normalized differential vegetation index were the best for the Sentinel MSI. The total accuracy evaluation of the fire severity assessment for Gaofen-1 WFV ranged from 40 to 44% and that for Sentinel MSI ranged from 40 to 48%. The difference in accuracy between the two satellites was less than 10%. The RMSE values for all six models were close to 0.6, ranging from 0.58 to 0.67. The fire severity maps derived from both imagery sources exhibited overall similar spatial patterns, but the Sentinel-2 MSI maps are obviously finer. These maps matched well with the unmanned aerial vehicle (UAV) images, particularly at high and unburned severity levels. The results of this study revealed that the performance of the Gaofen WFV imagery was close to that of Sentinel MSI imagery which makes it an effective data source for fire severity assessment in this region.